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EP4324645A1 - Structure creuse pour combustible - Google Patents

Structure creuse pour combustible Download PDF

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Publication number
EP4324645A1
EP4324645A1 EP22787914.5A EP22787914A EP4324645A1 EP 4324645 A1 EP4324645 A1 EP 4324645A1 EP 22787914 A EP22787914 A EP 22787914A EP 4324645 A1 EP4324645 A1 EP 4324645A1
Authority
EP
European Patent Office
Prior art keywords
polyamide resin
resin layer
layer
structural unit
mass
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP22787914.5A
Other languages
German (de)
English (en)
Other versions
EP4324645A4 (fr
Inventor
Momoko Yamashita
NAKAMURA Jin SHIMADA
Takafumi Oda
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Gas Chemical Co Inc
Original Assignee
Mitsubishi Gas Chemical Co Inc
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Publication date
Application filed by Mitsubishi Gas Chemical Co Inc filed Critical Mitsubishi Gas Chemical Co Inc
Publication of EP4324645A1 publication Critical patent/EP4324645A1/fr
Publication of EP4324645A4 publication Critical patent/EP4324645A4/fr
Withdrawn legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0013—Extrusion moulding in several steps, i.e. components merging outside the die
    • B29C48/0015—Extrusion moulding in several steps, i.e. components merging outside the die producing hollow articles having components brought in contact outside the extrusion die
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/022—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the choice of material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
    • B29C48/18—Articles comprising two or more components, e.g. co-extruded layers the components being layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B1/00—Layered products having a non-planar shape
    • B32B1/08—Tubular products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
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    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B32B27/22—Layered products comprising a layer of synthetic resin characterised by the use of special additives using plasticisers
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/34—Layered products comprising a layer of synthetic resin comprising polyamides
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/02—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by features of form at particular places, e.g. in edge regions
    • B32B3/04—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by features of form at particular places, e.g. in edge regions characterised by at least one layer folded at the edge, e.g. over another layer ; characterised by at least one layer enveloping or enclosing a material
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C08K3/041—Carbon nanotubes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/26—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers modified by chemical after-treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
    • C08L77/02—Polyamides derived from omega-amino carboxylic acids or from lactams thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
    • C08L77/06—Polyamides derived from polyamines and polycarboxylic acids
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
    • F02M37/0011—Constructional details; Manufacturing or assembly of elements of fuel systems; Materials therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L11/00—Hoses, i.e. flexible pipes
    • F16L11/04—Hoses, i.e. flexible pipes made of rubber or flexible plastics
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L11/00—Hoses, i.e. flexible pipes
    • F16L11/04—Hoses, i.e. flexible pipes made of rubber or flexible plastics
    • F16L11/12—Hoses, i.e. flexible pipes made of rubber or flexible plastics with arrangements for particular purposes, e.g. specially profiled, with protecting layer, heated, electrically conducting
    • F16L11/127—Hoses, i.e. flexible pipes made of rubber or flexible plastics with arrangements for particular purposes, e.g. specially profiled, with protecting layer, heated, electrically conducting electrically conducting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L9/00—Rigid pipes
    • F16L9/12—Rigid pipes of plastics with or without reinforcement
    • F16L9/121—Rigid pipes of plastics with or without reinforcement with three layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2077/00—Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/03—3 layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
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    • B32B2250/00—Layers arrangement
    • B32B2250/24—All layers being polymeric
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/10—Inorganic particles
    • B32B2264/107—Ceramic
    • B32B2264/108—Carbon, e.g. graphite particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2270/00—Resin or rubber layer containing a blend of at least two different polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
    • B32B2307/308—Heat stability
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/554—Wear resistance
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    • B32B2307/714—Inert, i.e. inert to chemical degradation, corrosion
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L9/00—Rigid pipes
    • F16L9/12—Rigid pipes of plastics with or without reinforcement
    • F16L9/125—Rigid pipes of plastics with or without reinforcement electrically conducting

Definitions

  • the present invention relates to a hollow structure for fuel.
  • it relates to a hollow structure for liquid fuel.
  • aliphatic polyamides such as polyamide 11 and polyamide 12 have been used as materials for hollow structures for fuel transportation because of their excellent chemical resistance.
  • hollow structures formed from these aliphatic polyamides are excellent in toughness, chemical resistance and flexibility, but are not sufficient in fuel barrier properties, and improvement thereof has been desired.
  • xylylenediamine polyamide resins such as polymetaxylylene adipamide (MXD6) are known as resins having excellent fuel barrier properties.
  • Patent Document 1 discloses a multilayer structure (a pipe, a hose, or a tube) including a polyamide layer (A) and a polyamide layer (B), in which the polyamide layer (A) includes a polyamide composition (A) including at least one polyamide (A1) selected from the group including a polyamide (a1) containing at least one of a structural unit derived from a lactam having from 10 to 12 carbon atoms and a structural unit derived from an aminocarboxylic acid having from 10 to 12 carbon atoms and a polyamide (a2) containing a structural unit derived from an aliphatic diamine having from 6 to 12 carbon atoms and a structural unit derived from an aliphatic dicarboxylic acid having from 10 to 12 carbon atoms, and in which the polyamide layer (B) includes a polyamide composition (B) including: a polyamide resin (b1) including a diamine unit containing 70 mol% or more of a structural unit derived from xylylenedi
  • Patent Document 1 WO 2017/094564
  • the hollow structure for fuel as described above is required to have fuel barrier properties and low-temperature impact resistance. Further, in recent years, the hollow structure for fuel is required to have conductivity. In order to achieve conductivity, it is conceivable to blend a conductive substance into a polyamide resin layer which is an inner layer (usually, an innermost layer) of the hollow structure. However, it has been found that the low-temperature impact resistance of the hollow structure is deteriorated when a conductive substance is blended into the polyamide resin layer. In order to improve the low-temperature impact resistance, it is conceivable to reduce the thickness of the polyamide resin layer containing a conductive substance or to ensure the low-temperature impact resistance by providing a highly flexible resin as an outer layer.
  • the fuel barrier properties may be poor. Therefore, in order to ensure the fuel barrier properties, it is also conceivable to provide an intermediate layer between the polyamide resin layer containing a conductive substance and the outer layer. However, when the adhesion between the intermediate layer and the polyamide resin layer containing a conductive substance or between the intermediate layer and the outer layer is poor, the low-temperature impact resistance is poor. Further, when the amount of an eluate from the hollow structure is large, there is an issue that the eluate is eluted into the fuel. Examples of the eluate from the hollow structure include a low molecular weight product such as a monomer or oligomer derived from a resin, and a plasticizer used for flexibility modification.
  • An object of the present invention is to solve such issues and to provide a hollow structure for fuel which is excellent in fuel barrier properties and adhesion between respective layers, has a small amount of an eluate, and is excellent in low-temperature impact resistance.
  • the above issues have been solved by forming a structure having at least three polyamide resin layers, blending a conductive substance in an inner layer of the three layers, blending a polyamide resin having high fuel barrier properties and a polyolefin in an intermediate layer of the three layers, and using a polyamide resin having high flexibility in an outer layer of the three layers.
  • the present invention it is possible to provide a hollow structure for fuel which is excellent in fuel barrier properties and adhesion between respective layers, has a small amount of an eluate, and is excellent in low-temperature impact resistance.
  • the hollow structure in the present specification is a structure having a hollow structure, is preferably sufficiently long in a longitudinal direction with respect to a cross section, includes a tube, a pipe, a hose, and the like, and is preferably a tube.
  • the hollow structure for fuel (hereinafter, sometimes simply referred to as "hollow structure") of the present embodiments is a hollow structure for fuel including a polyamide resin layer (A), a polyamide resin layer (B), and a polyamide resin layer (C) in this order from an outside, in which the polyamide resin layer (A) contains a polyamide resin (a), 90 mol% or more of all structural units of the polyamide resin (a) being one or more of: a structural unit derived from a lactam having from 10 to 12 carbon atoms; a structural unit derived from an aminocarboxylic acid having from 10 to 12 carbon atoms; a structural unit derived from an aliphatic dicarboxylic acid having from 6 to 12 carbon atoms; and a structural unit derived from an aliphatic diamine having from 6 to 12 carbon atoms; in which the polyamide resin layer (B) contains a polyolefin, a polyamide (b1), and a polyamide (b2); a content of the polyo
  • the hollow structure for fuel in the present embodiments includes a polyamide resin layer (A) (hereinafter sometimes simply referred to as “layer (A)”), a polyamide resin layer (B) (hereinafter sometimes simply referred to as “layer (B)”), and a polyamide resin layer (C) (hereinafter sometimes simply referred to as “layer (C)”) in this order from the outside.
  • FIG. 1 is a schematic diagram illustrating an example of a cross section of the hollow structure for fuel of the present invention, in which "A” represents a polyamide resin layer (A), “B” represents a polyamide resin layer (B), and “C” represents a polyamide resin layer (C).
  • the polyamide resin layer (A) and the polyamide resin layer (B) may or may not be in contact with each other, but are usually in contact with each other.
  • an adhesive resin having an acid group or polyamide resin which adheres to both of the layers is preferably provided therebetween, and an adhesive resin having an acid group is more preferably provided therebetween.
  • the polyamide resin layer (B) and the polyamide resin layer (C) may or may not be in contact with each other, but are usually in contact with each other.
  • each of the polyamide resin layer (A), the polyamide resin layer (B), and the polyamide resin layer (C) may be one layer, or two or more layers.
  • a layer may be additionally present inside the layer (C) and/or outside the layer (A). However, it is preferable that no layer is provided inside the layer (C).
  • a preferable layer configuration of the hollow structure of the present embodiments has the polyamide resin layer (A), the polyamide resin layer (B), and the polyamide resin layer (C) in this order from the outside, and it is preferable that the polyamide resin layer (A) and the polyamide resin layer (B) are in contact with each other, and that the polyamide resin layer (B) and the polyamide resin layer (C) are in contact with each other. Furthermore, it is preferable that no layer is provided outside the polyamide resin layer (C), that is, the polyamide resin layer (C) is the innermost layer.
  • a layer configuration further having a layer provided inside the layer (C) is also preferable. Further, in the above layer configuration, a layer configuration further having a layer outside the layer (A) is also preferable.
  • the hollow structure of the present embodiments has a layer other than the layers (A) to (C)
  • the layer include resin layers containing thermoplastic resins such as maleic anhydride-modified polyolefin, fluororesin, polyimide, polyamide, polyester, polystyrene, and vinyl chloride, and adhesive layers.
  • the polyamide resin layer (A) contains a polyamide resin (a), and 90 mol% or more of all structural units of the polyamide resin (a) are one or more of a structural unit derived from a lactam having from 10 to 12 carbon atoms, a structural unit derived from an aminocarboxylic acid having from 10 to 12 carbon atoms, a structural unit derived from an aliphatic dicarboxylic acid having from 6 to 12 carbon atoms, and a structural unit derived from an aliphatic diamine having from 6 to 12 carbon atoms.
  • 90 mol% or more of all structural units are one or more of a structural unit derived from a lactam having from 10 to 12 carbon atoms, a structural unit derived from an aminocarboxylic acid having from 10 to 12 carbon atoms, a structural unit derived from an aliphatic dicarboxylic acid having from 6 to 12 carbon atoms, and a structural unit derived from an aliphatic diamine having from 6 to 12 carbon atoms, and it is preferable that 95 mol% or more of all the structural units include the above structural units, and it is more preferable that 99 mol% or more of all the structural units include the above structural units.
  • At least one of the structural units preferably has from 10 to 12 carbon atoms.
  • a hollow structure more excellent in gas barrier properties is obtained by adopting such a configuration.
  • the polyamide resin (a) more preferably contains the following polyamide resins (a1) and/or (a2), and even more preferably contains the following polyamide resin (a1):
  • the number of carbon atoms of the structural unit derived from a lactam having from 10 to 12 carbon atoms and the structural unit derived from an aminocarboxylic acid having from 10 to 12 carbon atoms is preferably from 11 to 12 carbon atoms, and more preferably 12 carbon atoms from the perspective of flexibility, availability, and the like.
  • the structural unit derived from a lactam having from 10 to 12 carbon atoms and the structural unit derived from an aminocarboxylic acid having from 10 to 12 carbon atoms usually include an ⁇ -aminocarboxylic acid unit represented by Formula (I) below:
  • p represents an integer of from 9 to 11, preferably from 10 to 11, and more preferably 11.
  • the polyamide resin (a1) may contain only one or two or more structural unit(s) represented by Formula (I).
  • a compound constituting the structural unit derived from a lactam having from 10 to 12 carbon atoms include decanelactam, undecanelactam, and dodecanelactam.
  • Examples of a compound constituting the structural unit derived from an aminocarboxylic acid having from 10 to 12 carbon atoms include 10-aminodecanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.
  • the polyamide resin (a1) may contain a structural unit other than the lactam-derived structural unit and the aminocarboxylic acid-derived structural unit.
  • the other structural unit include a structural unit derived from a lactam other than the lactam having from 10 to 12 carbon atoms, a structural unit derived from an aminocarboxylic acid other than the aminocarboxylic acid having from 10 to 12 carbon atoms, a structural unit derived from a diamine, and a structural unit derived from a dicarboxylic acid.
  • lactams other than the lactam having from 10 to 12 carbon atoms include lactams having 3 to 9 carbon atoms, and specific examples thereof include ⁇ -caprolactam, ⁇ -enantholactam, ⁇ -pyrrolidone, and ⁇ -piperidone.
  • lactams having 3 to 9 carbon atoms include lactams having 3 to 9 carbon atoms, and specific examples thereof include ⁇ -caprolactam, ⁇ -enantholactam, ⁇ -pyrrolidone, and ⁇ -piperidone.
  • aminocarboxylic acid other than the aminocarboxylic acid having from 10 to 12 carbon atoms include 6-aminocaproic acid, 7-aminoheptanoic acid, and 9-aminononanoic acid. One of these can be used alone, or two or more thereof can be used in combination.
  • diamine examples include aliphatic diamines such as ethylene diamine, propylene diamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, 1,15-pentadecanediamine, 1,16-hexadecanediamine, 1,17-heptadecanediamine, 1,18-octadecanediamine, 1,19-nonadecanediamine, 1,20-eicosanediamine, 2-methyl-1,5-pentanediamine, 3-methyl-1,5-pentanediamine, 2-methyl-1,8-octanediamine and 2,2,4- or 2,4,4-trimethylhexanediamine; cycloaliphatic diamines such as 1,3- or 1,
  • dicarboxylic acid examples include aliphatic dicarboxylic acids such as adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1, 9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid and 1,12-dodecanedicarboxylic acid; alicyclic dicarboxylic acids such as 1,3-or 1,4-cyclohexanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid and norbornanedicarboxylic acid; and aromatic dicarboxylic acids such as isophthalic acid, terephthalic acid and 1,4 -, 2,6-or 2,7-naphthalenedicarboxylic acid. One of these can be used alone, or two or more thereof can be used in combination.
  • the polyamide resin (a1) is preferably polyamide 11 containing at least one of an undecanelactam-derived structural unit and a 11-aminoundecanoic acid-derived structural unit as a main component, polyamide 12 containing at least one of a dodecanelactam-derived structural unit and a 12-aminododecanoic acid-derived structural unit as a main component, or a mixture of the polyamide 11 and the polyamide 12, and more preferably polyamide 12.
  • polyamide resin (a1) As for the polyamide resin (a1), reference can be made to the descriptions in paragraphs [0011] to [0019] of WO 2017/094564 , the contents of which are incorporated herein by reference.
  • polyamide resins (a2) 90 mol% or more of all structural units are a structural unit derived from an aliphatic dicarboxylic acid having from 6 to 12 carbon atoms and a structural unit derived from an aliphatic diamine having from 6 to 12 carbon atoms.
  • At least one of the structural unit derived from the aliphatic dicarboxylic acid having from 6 to 12 carbon atoms and the structural unit derived from the aliphatic diamine having from 6 to 12 carbon atoms preferably has from 10 to 12 carbon atoms, and more preferably both the structural unit derived from the aliphatic dicarboxylic acid having from 6 to 12 carbon atoms and the structural unit derived from the aliphatic diamine having from 6 to 12 carbon atoms have from 10 to 12 carbon atoms.
  • the aliphatic dicarboxylic acid having from 6 to 12 carbon atoms is preferably an aliphatic dicarboxylic acid having from 10 to 12 carbon atoms, and more preferably adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, or the like.
  • the polyamide resin (a2) may contain only one or two or more structural unit(s) derived from an aliphatic dicarboxylic acid having from 6 to 12 carbon atoms.
  • Examples of the dicarboxylic acid other than the aliphatic dicarboxylic acid having from 6 to 12 carbon atoms include aliphatic dicarboxylic acids having 5 or less carbon atoms or 13 or more carbon atoms, and aromatic dicarboxylic acids.
  • Examples of the aliphatic dicarboxylic acid having 5 or less carbon atoms or 13 or more carbon atoms include succinic acid, glutaric acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, and 1,14-tetradecanedicarboxylic acid.
  • Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. One of these can be used alone, or two or more thereof can be used in combination.
  • the aliphatic group constituting the aliphatic diamine having from 6 to 12 carbon atoms is a linear or branched divalent aliphatic hydrocarbon group, and may be a saturated aliphatic group or an unsaturated aliphatic group, but is usually a linear saturated aliphatic group.
  • the number of carbon atoms of the aliphatic group is preferably from 8 to 12, more preferably from 9 to 12, and even more preferably from 10 to 12.
  • Examples of a compound that can constitute the diamine-derived structural unit of the polyamide resins (a2) include hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, and undecamethylenediamine. One of these can be used alone, or two or more thereof can be used in combination.
  • the polyamide resin (a2) may contain a structural unit derived from an aliphatic diamine other than the structural unit derived from an aliphatic diamine having from 6 to 12 carbon atoms.
  • diamines other than the aliphatic diamine having from 6 to 12 carbon atoms can include, but are not limited to, alicyclic diamines such as ethylenediamine, propylenediamine, tetramethylenediamine, pentamethylenediamine, 1,3- or 1,4-bis(aminomethyl)cyclohexane, 1,3- or 1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminomethyl)decalin, and bis(aminomethyl)tricyclodecane.; and diamines having an aromatic ring such as bis(4-aminophenyl)ether, paraphenylenedi
  • polyamide resin (a2) As for the polyamide resin (a2), reference can be made to the descriptions in paragraphs [0020] to [0027] of WO 2017/094564 , the contents of which are incorporated herein by reference.
  • a content of the polyamide resin (a) in the polyamide resin layer (A) is preferably 50 mass% or more, more preferably 55 mass% or more, even more preferably 60 mass% or more, still more preferably 65 mass% or more, and even still more preferably 70 mass% or more.
  • the polyamide resin layer (A) tends to be more excellent in adhesion to the polyamide resin layer (B) while the fuel barrier properties of the polyamide resin layer (A) are ensured to some extent or more.
  • the content of the polyamide resin (a) in the polyamide resin layer (A) is preferably 95 mass% or less, more preferably 90 mass% or less, even more preferably 86 mass% or less, and still more preferably 84 mass% or less.
  • an impact resistance modifier for example, polyolefin
  • the obtained hollow structure tends to be more excellent in low-temperature impact resistance.
  • the polyamide resin layer (A) may contain only one or two or more polyamide resin(s) (a). When two or more polyamide resins are contained, the total amount thereof is preferably in the above range.
  • the polyamide resin layer (A) may also contain a polyolefin. By including a polyolefin in the polyamide resin layer (A), the low-temperature impact resistance can be further improved.
  • the polyolefin is preferably a homopolymer and/or a copolymer of an ⁇ -olefin such as ethylene, propylene or butene.
  • polyethylene As the polyethylene, it is possible to use low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), or the like.
  • LDPE low density polyethylene
  • LLDPE linear low density polyethylene
  • VLDPE very low density polyethylene
  • MDPE medium density polyethylene
  • HDPE high density polyethylene
  • a copolymer of at least two of ethylene, propylene and butene, or a copolymer of at least one of ethylene, propylene and butene and a monomer copolymerizable therewith can be used.
  • the monomer that can be copolymerized with at least one of ethylene, propylene, and butene include ⁇ -olefins, styrenes, dienes, cyclic compounds, and oxygen atom-containing compounds.
  • Particularly preferred copolymers include ethylene/butene copolymers and ethylene/propylene copolymers, with ethylene/butene copolymers being preferred.
  • the copolymer may be any of an alternating copolymer, a random copolymer, and a block copolymer.
  • the polyolefin is preferably an acid-modified polyolefin.
  • the acid-modified polyolefin is preferably a polyolefin acid-modified with a carboxylic acid and/or a derivative thereof, and a polyolefin acid-modified with a carboxylic acid and/or a derivative thereof and further having a polyamide graft-bonded thereto via a functional group introduced into the molecule by the acid modification (also referred to as "polyamide-graft-modified polyolefin").
  • a functional group having affinity for the polyamide resin (b) contained in the polyamide resin layer (B) can be introduced into the molecule.
  • the affinity for the polyamide resin (b) can be further increased.
  • Preferred examples of the functional group having affinity for the polyamide component include a carboxylic acid group, a carboxylic anhydride group, a carboxylic acid ester group, a carboxylic acid metal salt group, a carboxylic acid imide group, a carboxylic acid amide group, and an epoxy group.
  • Preferred examples of a compound capable of acid-modifying a polyolefin include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, methylmaleic acid, methylfumaric acid, mesaconic acid, citraconic acid, glutaconic acid, cis-4-cyclohexene-1,2-dicarboxylic acid, endobicyclo[2.2.1]-5-heptene-2,3-dicarboxylic acid and metal salts of these carboxylic acids, monomethyl maleate, monomethyl itaconate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, methyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, aminoethyl methacrylate, dimethyl maleate, dimethyl itaconate, maleic anhydride
  • the acid-modified polyolefin particularly preferably used in the embodiments include maleic anhydride-modified polyethylene, maleic anhydride-modified ⁇ -olefin copolymers such as maleic anhydride-modified ethylene/butene copolymers, and polyolefins graft-modified with aliphatic polyamides, from the perspective of elastic modulus, flexibility, and impact resistance.
  • maleic anhydride-modified ethylene/butene copolymers are particularly preferably used.
  • a content of the polyolefin is preferably 4 mass% or more, more preferably 7 mass% or more, even more preferably 10 mass% or more, and still more preferably 12 mass% or more.
  • the content of the polyolefin in the polyamide resin layer (A) is preferably 30 mass% or less, more preferably 25 mass% or less, even more preferably 22 mass% or less, still more preferably 20 mass% or less,and even still more preferably 17 mass% or less.
  • the proportion of the polyamide resin (a) can be relatively increased, and the polyamide resin (a) can effectively exert its inherent fuel barrier properties.
  • the polyamide resin layer (A) may contain only one or two or more polyolefin(s). When two or more polyolefins are contained, the total amount thereof is preferably in the above range.
  • the polyamide resin layer (A) may contain a plasticizer.
  • a plasticizer in the polyamide resin layer (A)
  • the low-temperature impact resistance can be further improved.
  • the polyamide resin layer (B) having excellent fuel barrier properties the amount of an eluate can be reduced even when a plasticizer is blended in the polyamide resin layer (A). That is, the fuel moves into the layer (C), the layer (B), and the layer (A) in this order, takes in the plasticizer, returns to the layer (B) and the layer (C) in this order, and can become an eluate eluted into the tube.
  • the polyamide resin layer (B) having a high barrier function allows the movement of the fuel through the layers to be effectively suppressed, and the amount of the eluate can be suppressed to be low even when the plasticizer is blended.
  • plasticizer examples include benzenesulfonic acid alkylamide, toluenesulfonic acid alkylamide, and hydroxybenzoic acid alkyl ester, and benzenesulfonic acid alkylamide is preferable.
  • benzenesulfonic acid alkylamide examples include benzenesulfonic acid propylamide, benzenesulfonic acid butylamide (N-butylbenzenesulfonamide), and benzenesulfonic acid 2-ethylhexylamide.
  • Examples of the toluenesulfonic acid alkylamide include N-ethyl-o-toluenesulfonic acid butylamide, N-ethyl-p-toluenesulfonic acid butylamide, N-ethyl-o-toluenesulfonic acid 2-ethylhexylamide, and N-ethyl-p-toluenesulfonic acid 2-ethylhexylamide.
  • hydroxybenzoic acid alkyl ester examples include ethylhexyl o-hydroxybenzoate, ethylhexyl p-hydroxybenzoate, hexyldecyl o-hydroxybenzoate, hexyldecyl p-hydroxybenzoate, ethyldecyl o-hydroxybenzoate, ethyldecyl p-hydroxybenzoate, octyloctyl o-hydroxybenzoate, octyloctyl p-hydroxybenzoate, decyldodecyl o-hydroxybenzoate, decyldodecyl p-hydroxybenzoate, methyl o-hydroxybenzoate, methyl p-hydroxybenzoate, butyl o-hydroxybenzoate, butyl p-hydroxybenzoate, hexyl o-hydroxybenzoate, hexyl p-hydroxybenzoate,
  • a content of the plasticizer is preferably 1 mass% or more, more preferably 2 mass% or more, even more preferably 3 mass% or more, and still more preferably 4 mass% or more.
  • the content of the plasticizer in the polyamide resin layer (A) is preferably 20 mass% or less, more preferably 18 mass% or less, even more preferably 17 mass% or less, still more preferably 16 mass% or less, and even still more preferably 15 mass% or less.
  • the amount of the eluate can be made smaller.
  • the polyamide resin layer (A) may contain only one or two or more plasticizer(s). When two or more plasticizers are contained, the total amount thereof is preferably in the above range.
  • a mass ratio between the polyolefin and the plasticizer in the polyamide resin layer (A) is preferably from 1:0.2 to 1:3.5, more preferably from 1:0.2 to 1:2.0, even more preferably from 1:0.3 to 1:0.95, and still more preferably from 1:0.4 to 1:0.8.
  • the amount of the eluate can be effectively reduced while the low-temperature impact resistance can be effectively maintained.
  • the polyamide resin layer (A) may contain other components in addition to the above components.
  • the other components include a thermoplastic resin other than the polyamide resin (a), a conductive substance, an antioxidant, a heat stabilizer, an ultraviolet absorber, a light stabilizer, a lubricant, an inorganic filler, an antistatic agent, a flame retardant, a compatibilizer, a crystallization accelerator, and an impact resistance modifier other than the polyolefin.
  • a total content of these other components is preferably 20 mass% or less, more preferably 15 mass% or less, and even more preferably 12 mass% or less.
  • a total content of the polyamide resin (a) and the polyolefin and the plasticizer which are blended as necessary accounts for preferably 90 mass% or more, more preferably 95 mass% or more, even more preferably 98 mass% or more, and still more preferably 99 mass% or more of the layer (A) .
  • the polyamide resin layer (A) is preferably substantially free of conductive substance.
  • substantially free means that the content of the conductive substance contained in the polyamide resin layer (C) is 10 mass% or less, preferably 5 mass% or less, more preferably 3 mass% or less, and even more preferably 1 mass% or less.
  • a thickness of the polyamide resin layer (A) is preferably 10% or more, more preferably 30% or more, even more preferably 40% or more, still more preferably 50% or more, and even still more preferably 60% or more when a total thickness of the hollow structure is defined as 100%.
  • the thickness of the polyamide resin layer (A) is preferably 90% or less, more preferably 85% or less, even more preferably 80% or less, still more preferably 75% or less, and even still more preferably 72% or less when the total thickness of the hollow structure is defined as 100%.
  • the barrier layer and the conductive layer can be laminated with a functional thickness, and the fuel barrier properties and the conductivity tend to be further improved.
  • the thickness of the polyamide resin layer (A) is preferably 100 ⁇ m or more, more preferably 300 ⁇ m or more, even more preferably 400 um or more, still more preferably 500 um or more, and even still more preferably 600 ⁇ m or more. Also, the thickness of the polyamide resin layer (A) is preferably 3000 ⁇ m or less, more preferably 2000 um or less, even more preferably 1100 um or less, still more preferably 900 ⁇ m or less, and even still more preferably 800 ⁇ m or less.
  • the polyamide resin layer (B) contains a polyolefin, a polyamide resin (b1), and a polyamide resin (b2).
  • a content of the polyolefin is from 5 to 40 mass% of the polyamide resin layer (B), and a mass ratio (b1/b2) between a content of the polyamide resin (b1) and a content of the polyamide resin (b2) is from 55/45 to 95/5.
  • the polyamide resin (b1) contains: a diamine-derived structural unit containing 70 mol% or more of a structural unit derived from metaxylylenediamine; and a dicarboxylic acid-derived structural unit containing 70 mol% or more of a structural unit derived from an aliphatic dicarboxylic acid having from 4 to 8 carbon atoms.
  • the polyamide resin (b2) contains: a diamine-derived structural unit containing 70 mol% or more of a structural unit derived from xylylenediamine; and a dicarboxylic acid-derived structural unit containing 70 mol% or more of a structural unit derived from an aliphatic dicarboxylic acid having from 9 to 12 carbon atoms.
  • the polyamide resin layer (B) contains a polyolefin.
  • a polyolefin By including a polyolefin, the low-temperature impact resistance of the hollow structure can be further improved.
  • the polyolefin is preferably an acid-modified polyolefin.
  • the details of the polyolefin are synonymous with those described for the polyamide resin layer (A), and preferred ranges are also the same.
  • a content of the polyolefin in the polyamide resin layer (B) is preferably 5 mass% or more, more preferably 6 mass% or more, even more preferably 7 mass% or more, and still more preferably 8 mass% or more. When the content is equal to or more than the lower limit value, the low-temperature impact resistance tends to be further improved.
  • the content of the polyolefin in the polyamide resin layer (B) is preferably 40 mass% or less, more preferably 35 mass% or less, even more preferably 28 mass% or less, still more preferably 25 mass% or less, and even still more preferably 18 mass% or less. When the content is equal to or less than the upper limit value, the fuel barrier properties can be further improved, and the amount of the eluate can be more effectively suppressed.
  • the polyamide resin layer (B) may contain only one or two or more polyolefin(s). When two or more polyolefins are contained, the total amount thereof is preferably in the above range.
  • the layer (B) contains the polyamide resins (b1) and (b2), and the mass ratio (b1/b2) between the content of the polyamide resin (b1) and the content of the polyamide resin (b2) is from 55/45 to 95/5.
  • the polyamide resin (b1) By blending the polyamide resin (b1), a hollow structure having excellent fuel barrier properties and a small amount of an eluate can be obtained.
  • the adhesion between the layers (A) and (C) is improved by blending the polyamide resin (b2).
  • the mass ratio (b1/b2) between the content of the polyamide resin (b1) and the content of the polyamide resin (b2) is set to the above-described predetermined ratio, and thus the fuel barrier properties and the adhesion can be achieved in a well-balanced manner.
  • the diamine-derived structural unit contains 70 mol% or more of a structural unit derived from metaxylylenediamine
  • the dicarboxylic acid-derived structural unit contains 70 mol% or more of a structural unit derived from an aliphatic dicarboxylic acid having from 4 to 8 carbon atoms.
  • the proportion of the structural unit derived from metaxylylenediamine in the diamine-derived structural unit is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and still more preferably 98 mol% or more.
  • the polyamide resin (b1) may contain a diamine unit other than the structural unit derived from metaxylylenediamine.
  • the diamine unit include diamine units derived from compounds such as aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, 2-methyl-1,5-pentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, and 2,2,4- or 2,4,4-trimethylhexamethylenediamine; alicyclic diamines such as 1,3- or 1,4-bis(aminomethyl)cyclohexane, 1,3- or 1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminomethyl)decalin, and
  • the proportion of the structural unit derived from an aliphatic dicarboxylic acid having from 4 to 8 carbon atoms (preferably, adipic acid) in the dicarboxylic acid-derived structural unit is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and still more preferably 98 mol% or more.
  • the aliphatic dicarboxylic acid having from 4 to 8 carbon atoms is preferably an ⁇ , ⁇ -linear aliphatic dicarboxylic acid having from 4 to 8 carbon atoms.
  • the ⁇ , ⁇ -linear aliphatic dicarboxylic acid having from 4 to 8 carbon atoms is, for example, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, or the like, and is preferably adipic acid.
  • succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, or the like is preferably adipic acid.
  • One of these can be used alone, or two or more thereof can be used in combination.
  • the polyamide resin (b1) may contain a dicarboxylic acid unit other than the structural unit derived from an aliphatic dicarboxylic acid having from 4 to 8 carbon atoms.
  • dicarboxylic acid units other than the structural unit derived from an aliphatic dicarboxylic acid having from 4 to 8 carbon atoms include aliphatic dicarboxylic acids having 3 or less carbon atoms such as oxalic acid and malonic acid; aliphatic carboxylic acids having 9 or more carbon atoms such as azelaic acid, sebacic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, and 1,14-tetradecanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. One of these can be used alone, or two or more thereof can be used in combination.
  • the diamine-derived structural unit contains 70 mol% or more of a structural unit derived from xylylenediamine
  • the dicarboxylic acid-derived structural unit contains 70 mol% or more of a structural unit derived from an aliphatic dicarboxylic acid having from 9 to 12 carbon atoms.
  • the proportion of the structural unit derived from metaxylylenediamine in the diamine-derived structural unit is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and still more preferably 98 mol% or more.
  • the polyamide resin (b2) may contain a diamine unit other than the structural unit derived from metaxylylenediamine.
  • the diamine unit include diamine units derived from compounds such as aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, 2-methyl-1,5-pentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, and 2,2,4- or 2,4,4-trimethylhexamethylenediamine; alicyclic diamines such as 1,3- or 1,4-bis(aminomethyl)cyclohexane, 1,3- or 1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminomethyl)decalin, and
  • the proportion of the structural unit derived from an aliphatic dicarboxylic acid having from 9 to 12 carbon atoms (preferably, sebacic acid) in the dicarboxylic acid-derived structural unit is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and still more preferably 98 mol% or more.
  • the aliphatic dicarboxylic acid having from 9 to 12 carbon atoms is preferably an ⁇ , ⁇ -linear aliphatic dicarboxylic acid having from 9 to 12 carbon atoms.
  • Examples of the ⁇ , ⁇ -linear aliphatic dicarboxylic acid having from 9 to 12 carbon atoms include azelaic acid, sebacic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, and 1,12-dodecanedicarboxylic acid, and sebacic acid is preferable.
  • One of these can be used alone, or two or more thereof can be used in combination.
  • the polyamide resin (b2) may contain a dicarboxylic acid unit other than the structural unit derived from an aliphatic dicarboxylic acid having from 9 to 12 carbon atoms.
  • dicarboxylic acid unit other than the structural unit derived from an aliphatic dicarboxylic acid having from 9 to 12 carbon atoms examples include aliphatic dicarboxylic acids having 8 or less carbon atoms such as succinic acid, glutaric acid, adipic acid, pimelic acid, and suberic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. One of these can be used alone, or two or more thereof can be used in combination.
  • the mass ratio (b1/b2) between the content of the polyamide resin (b1) and the content of the polyamide resin (b2) is from 55/45 to 95/5, preferably from 55/45 to 89/11, and more preferably from 55/45 to 85/15, and may be from 65/35 to 85/15.
  • a total content of the polyamide resins (b1) and (b2) in the polyamide resin layer (B) is preferably 60 mass% or more, more preferably 65 mass% or more, even more preferably 75 mass% or more, still more preferably 80 mass% or more, and even still more preferably 85 mass% or more.
  • the total content is equal to or more than the lower limit value, the fuel barrier properties can be improved, the amount of the eluate can be further reduced, and the adhesion of the polyamide resin layer (B) to the polyamide resin layer (A) or (C) tends to be further improved.
  • the total content of the polyamide resins (b1) and (b2) in the polyamide resin layer (B) is preferably 95 mass% or less, more preferably 94 mass% or less, even more preferably 93 mass% or less, and still more preferably 92 mass% or less.
  • the total content is equal to or less than the upper limit value, an impact resistance modifier can be sufficiently blended, and the low-temperature impact resistance tends to be more excellent.
  • the polyamide resin layer (B) may contain one or two or more of each of the polyamide resins (b1) and (b2). When two or more of each of the polyamide resins (b1) and (b2) are contained, the total amount thereof is preferably in the above range.
  • the polyamide resin layer (B) may contain other components in addition to the above components.
  • the other components include a thermoplastic resin other than the polyamide resins (b1) and (b2), a conductive substance, a plasticizer, an antioxidant, a heat stabilizer, an ultraviolet absorber, a light stabilizer, a lubricant, an inorganic filler, an antistatic agent, a flame retardant, a crystallization accelerator, and an impact resistance modifier other than the polyolefin.
  • a total content of these other components is preferably 20 mass% or less, more preferably 15 mass% or less, and even more preferably 12 mass% or less.
  • a total content of the polyamide resin (b1), the polyamide resin (b2), and the polyolefin accounts for preferably 90 mass% or more, more preferably more than 95 mass%, even more preferably 98 mass% or more, and still more preferably 99 mass% or more of the layer (B).
  • the polyamide resin layer (B) is preferably substantially free of conductive substance.
  • substantially free means that the content of the conductive substance contained in the polyamide resin layer (C) is 10 mass% or less, preferably 5 mass% or less, more preferably 3 mass% or less, and even more preferably 1 mass% or less.
  • the polyamide resin layer (B) is preferably substantially free of plasticizer.
  • substantially free means that the content of the plasticizer is 0.1 mass% or less, preferably 0.05 mass% or less, more preferably 0.03 mass% or less, and even more preferably 0.01 mass% or less of the polyamide resin layer (B) .
  • a thickness of the polyamide resin layer (B) is preferably 3% or more, more preferably 5% or more, even more preferably 10% or more, still more preferably 15% or more, and even still more preferably 18% or more when a total thickness of the hollow structure is defined as 100%.
  • the thickness of the polyamide resin layer (B) is preferably 50% or less, more preferably 40% or less, even more preferably 35% or less, still more preferably 30% or less, and even still more preferably 26% or less when the total thickness of the hollow structure is defined as 100%.
  • the resin layer (A) can be laminated with a functional thickness, and both high fuel barrier properties and low-temperature impact resistance tend to be achieved.
  • the thickness of the polyamide resin layer (B) is preferably 30 um or more, more preferably 100 ⁇ m or more, even more preferably 130 ⁇ m or more, still more preferably 150 um or more, and even still more preferably 180 ⁇ m or more. Also, the thickness of the polyamide resin layer (B) is preferably 1000 ⁇ m or less, more preferably 800 ⁇ m or less, even more preferably 700 um or less, still more preferably 400 ⁇ m or less, and even still more preferably 300 um or less.
  • the polyamide resin layer (C) contains a conductive substance and a polyamide resin (c).
  • the polyamide resin layer (C) contains a conductive substance. By including a conductive substance, the conductivity can be imparted to the hollow structure.
  • Examples of the conductive substance used in the present embodiments include metals, metal oxides, conductive carbon compounds, and conductive polymers, and conductive carbon compounds are preferable.
  • the metal is preferably a metal filler, a stainless fiber, or a magnetic filler.
  • the metal oxide include alumina and zinc oxide, and alumina fibers and zinc oxide nanotubes are preferable.
  • the conductive carbon compound is preferably carbon black, Ketjen carbon, graphene, graphite, fullerenes, carbon nanocoils, carbon nanotubes, or carbon fibers, is more preferably carbon black and/or carbon nanotubes, and is even more preferably carbon black.
  • a content of the conductive substance in the polyamide resin layer (C) is preferably 2 mass% or more, and more preferably 3 mass% or more, and may be 7 mass% or more, in the polyamide resin layer (C).
  • the content of the conductive substance in the polyamide resin layer (C) is preferably 30 mass% or less, more preferably 28 mass% or less, even more preferably 25 mass% or less, still more preferably 23 mass% or less, and even still more preferably 21 mass% or less in the polyamide resin layer (C).
  • the content is equal to or less than the upper limit value, the cold-temperature impact resistance of the hollow structure tends to be further improved.
  • the polyamide resin layer (C) may contain only one or two or more conductive substance(s). When two or more conductive substances are contained, the total amount thereof is preferably in the above range.
  • the polyamide resin layer (C) contains a polyamide resin (c).
  • the polyamide resin (c) is a polyamide resin, the type and the like thereof are not particularly limited, and the polyamide resin (c) may be an aliphatic polyamide resin or an aromatic polyamide resin.
  • the aliphatic polyamide resin include polyamide 6, polyamide 66, polyamide 11, polyamide 12 and the like, and polyamide 66 is preferable.
  • semi-aromatic polyamide resins include polyamide 6T, polyamide 9T, polyamide 10T, polyamide 6I, polyamide 9I, polyamide 6T/6I, and polyamide 9T/9I.
  • 90 mol% or more of all structural units of the polyamide resin (c) are preferably one or more of a structural unit derived from a lactam having from 6 to 12 carbon atoms, a structural unit derived from an aminocarboxylic acid having from 6 to 12 carbon atoms, a structural unit derived from an aliphatic dicarboxylic acid having from 6 to 12 carbon atoms, and a structural unit derived from an aliphatic diamine having from 6 to 12 carbon atoms.
  • 90 mol% or more of all structural units are one or more of a structural unit derived from a lactam having from 6 to 12 carbon atoms, a structural unit derived from an aminocarboxylic acid having from 6 to 12 carbon atoms, a structural unit derived from an aliphatic dicarboxylic acid having from 6 to 12 carbon atoms, and a structural unit derived from an aliphatic diamine having from 6 to 12 carbon atoms, and it is preferable that 95 mol% or more of all the structural units include the above structural units, and it is more preferable that 99 mol% or more of all the structural units include the above structural units.
  • one of the structural units preferably has from 10 to 12 carbon atoms.
  • a hollow structure more excellent in gas barrier properties is obtained by adopting such a configuration.
  • the polyamide resin (c) more preferably contains the following polyamide resins (c1) and/or (c2), and even more preferably contains the following polyamide resin (c1):
  • the number of carbon atoms of the structural unit derived from a lactam having from 6 to 12 carbon atoms and the structural unit derived from an aminocarboxylic acid having from 6 to 12 carbon atoms is preferably from 11 to 12 carbon atoms, and more preferably 12 carbon atoms from the perspective of flexibility, availability, and the like.
  • the structural unit derived from a lactam having from 6 to 12 carbon atoms and the structural unit derived from an aminocarboxylic acid having from 6 to 12 carbon atoms usually include an ⁇ -aminocarboxylic acid unit represented by Formula (II) below:
  • q represents an integer of from 5 to 11, preferably an integer of from 9 to 11, more preferably from 10 to 11, and even more preferably 11.
  • the polyamide resin (c1) may contain only one or two or more structural unit(s) represented by Formula (II).
  • a compound constituting the structural unit derived from a lactam having from 6 to 12 carbon atoms include hexanlactam, heptalactam, octalactam, decanelactam, undecanelactam, and dodecanelactam.
  • Examples of a compound constituting the structural unit derived from an aminocarboxylic acid having from 6 to 12 carbon atoms include 6-aminocaproic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.
  • the polyamide resin (c1) may contain a structural unit other than the lactam-derived structural unit and the aminocarboxylic acid-derived structural unit.
  • the other structural unit include a structural unit derived from a lactam other than the lactam having from 6 to 12 carbon atoms, a structural unit derived from an aminocarboxylic acid other than the aminocarboxylic acid having from 6 to 12 carbon atoms, a structural unit derived from a diamine, and a structural unit derived from a dicarboxylic acid.
  • lactams other than the lactam having from 6 to 12 carbon atoms include lactams having 3 to 5 carbon atoms, and specific examples thereof include ⁇ -pyrrolidone and ⁇ -piperidone.
  • Examples of the diamine include the diamines described above for the polyamide resin (a1).
  • Examples of the dicarboxylic acid include the dicarboxylic acids described above for the polyamide resin (a1).
  • the polyamide resin (c1) is preferably polyamide 11 containing at least one of an undecanelactam-derived structural unit and a 11-aminoundecanoic acid-derived structural unit as a main component, polyamide 12 containing at least one of a dodecanelactam-derived structural unit and a 12-aminododecanoic acid-derived structural unit as a main component, or a mixture of the polyamide 11 and the polyamide 12, and more preferably polyamide 12.
  • polyamide resin (c1) As for the polyamide resin (c1), reference can be made to the descriptions in paragraphs [0011] to [0019] of WO 2017/094564 , the contents of which are incorporated herein by reference.
  • polyamide resins (c2) 90 mol% or more of all structural units are a structural unit derived from an aliphatic dicarboxylic acid having from 6 to 12 carbon atoms and a structural unit derived from an aliphatic diamine having from 6 to 12 carbon atoms.
  • At least one of the structural unit derived from the aliphatic dicarboxylic acid having from 6 to 12 carbon atoms and the structural unit derived from the aliphatic diamine having from 6 to 12 carbon atoms preferably has from 10 to 12 carbon atoms, and more preferably one of the structural unit derived from the aliphatic dicarboxylic acid having from 6 to 12 carbon atoms and the structural unit derived from the aliphatic diamine having from 6 to 12 carbon atoms have from 10 to 12 carbon atoms, and the structural unit derived from the aliphatic dicarboxylic acid having from 6 to 12 carbon atoms preferably has from 10 to 12 carbon atoms.
  • the aliphatic dicarboxylic acid having from 6 to 12 carbon atoms is preferably an aliphatic dicarboxylic acid having from 10 to 12 carbon atoms, and more preferably adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, or the like.
  • the polyamide resin (c2) may contain only one or two or more structural unit(s) derived from an aliphatic dicarboxylic acid having from 6 to 12 carbon atoms.
  • the dicarboxylic acids other than the aliphatic dicarboxylic acid having from 6 to 12 carbon atoms are synonymous with those described for the polyamide resin (a1), and preferred ranges are also the same.
  • the details of the aliphatic group constituting the aliphatic diamine having from 6 to 12 carbon atoms are synonymous with those described for the polyamide resin (a1), and preferred ranges are also the same.
  • the polyamide resin (c2) may contain a structural unit derived from an aliphatic diamine other than the structural unit derived from an aliphatic diamine having from 6 to 12 carbon atoms.
  • the details of these structural units are synonymous with those described for the polyamide resin (a1), and preferred ranges are also the same.
  • the amount of the eluate eluted from the polyamide resin layer (C) is particularly preferable to reduce the amount of the eluate eluted from the polyamide resin layer (C).
  • An example of a means for reducing the amount of the eluate eluted from the polyamide resin layer (C) is to reduce the amount of the eluate in the polyamide resin (c).
  • Examples of the eluate in the polyamide resin (c) include oligomers derived from the raw material for the polyamide resin (c).
  • the amount of the eluate in the polyamide resin (c) is preferably 25 g/m 2 or less, and more preferably 20 g/m 2 or less.
  • a lower limit value of the amount of the eluate in the polyamide resins (c) is ideally 0 g/m 2 , but the amount at which the eluate is not detected by the method described in Examples which will be described later will be substantially a lower limit value.
  • Examples of a means for achieving such an amount of the eluate include adjusting a method for synthesis of the polyamide resin (c) to make it difficult to produce a low molecular weight component, and washing the polyamide resin (c) after synthesis of the polyamide resin (c) (usually after preparation of pellets).
  • the washing may be performed by immersing the pellets in water or an alcohol (preferably a lower alcohol, more preferably methanol or ethanol, even more preferably methanol). At this time, heating may be performed.
  • the eluate can be more easily extracted by stirring.
  • a content of the polyamide resin (c) in the polyamide resin layer (C) is preferably 50 mass% or more, more preferably 55 mass% or more, even more preferably 60 mass% or more, and still more preferably 63 mass% or more, and may be 67 mass% or more.
  • the content of the polyamide resin (c) in the polyamide resin layer (C) is preferably 95 mass% or less, more preferably 90 mass% or less, and even more preferably 85 mass% or less, and may be 75 mass% or less.
  • the conductive substance and the impact resistance modifier can be sufficiently contained, and conductivity and cold-temperature impact resistance can be more effectively ensured.
  • the polyamide resin layer (C) may contain only one or two or more polyamide resin(s) (c). When two or more polyamide resins (c) are contained, the total amount thereof is preferably in the above range.
  • the layer (C) may also contain a polyolefin. By including a polyolefin, the low-temperature impact resistance can be further improved.
  • the polyolefin is preferably an acid-modified polyolefin.
  • the details of the polyolefin are synonymous with those described for the polyamide resin layer (A), and preferred ranges are also the same.
  • a content of the polyolefin is preferably 4 mass% or more, more preferably 6 mass% or more, even more preferably 7 mass% or more, and still more preferably 8 mass% or more.
  • the content of the polyolefin in the polyamide resin layer (C) is preferably 40 mass% or less, more preferably 35 mass% or less, even more preferably 28 mass% or less, still more preferably 25 mass% or less, and even still more preferably 18 mass% or less.
  • the adhesion of the polyamide resin layer (C) to the polyamide resin layer (B) tends to be more excellent.
  • the polyamide resin layer (C) may contain only one or two or more polyolefin(s). When two or more polyolefins are contained, the total amount thereof is preferably in the above range.
  • the polyamide resin layer (C) may contain other components in addition to the above components.
  • the other components include a thermoplastic resin other than the polyamide resin (c), a plasticizer, an antioxidant, a heat stabilizer, an ultraviolet absorber, a light stabilizer, a lubricant, an inorganic filler, an antistatic agent, a flame retardant, a crystallization accelerator, and an impact resistance modifier other than the polyolefin.
  • a total content of these other components is preferably 20 mass% or less, more preferably 15 mass% or less, and even more preferably 12 mass% or less.
  • a total content of the polyamide resin (c) and the conductive substance, as well as the polyolefin which is blended as necessary accounts for preferably 90 mass% or more, more preferably more than 95 mass%, even more preferably 97 mass% or more, and still more preferably 98 mass% or more of the layer (A).
  • the polyamide resin layer (C) is preferably substantially free of plasticizer.
  • substantially free means that the content of the plasticizer is 0.1 mass% or less, preferably 0.05 mass% or less, more preferably 0.03 mass% or less, and even more preferably 0.01 mass% or less of the polyamide resin layer (C) .
  • a thickness of the polyamide resin layer (C) is preferably 3% or more, more preferably 5% or more, even more preferably 7% or more, still more preferably 8% or more, and even still more preferably 9% or more when a total thickness of the hollow structure is defined as 100%.
  • the thickness of the polyamide resin layer (C) is preferably 30% or less, more preferably 25% or less, even more preferably 20% or less, still more preferably 18% or less, and even still more preferably 16% or less when the total thickness of the hollow structure is defined as 100%.
  • the content is equal to or less than the upper limit value, the hardness of the hollow structure tends to be reduced, and the cold-temperature impact resistance tends to be further improved.
  • the thickness of the polyamide resin layer (C) is preferably 20 um or more, more preferably 40 ⁇ m or more, even more preferably 50 ⁇ m or more, still more preferably 70 ⁇ m or more, and even still more preferably 80 ⁇ m or more. Also, the thickness of the polyamide resin layer (C) is preferably 500 um or less, more preferably 400 ⁇ m or less, even more preferably 300 um or less, still more preferably 200 ⁇ m or less, and even still more preferably 150 ⁇ m or less.
  • An amount of the eluate in an eluate test using a pseudo fuel in the hollow structure of the present embodiments is 25 g/m 2 or less.
  • Such a low amount of the eluate can be achieved, for example, by reducing the amount of the eluate in the polyamide resin (c) contained in the layer (C). That is, since the layer (C) is an inner layer, the amount of the eluate in the hollow structure can be effectively reduced by reducing the amount of the eluate in the layer (C).
  • the polyamide resin (b1) is blended into the layer (B) to enhance the fuel barrier properties. That is, when the fuel barrier properties of the layer (B) is low, the fuel moves from the layer (C) as the inner layer to the layer (A) via the layer (B), and returns to the layer (B) and the layer (C) in this order.
  • the fuel moves while containing a low molecular weight component contained in the layer (B) and/or the layer (A), particularly a compound such as a plasticizer, and returns to the layer (C).
  • a low molecular weight component contained in the layer (B) and/or the layer (A), particularly a compound such as a plasticizer returns to the layer (C).
  • the layer (C) contains a large amount of such a low molecular weight component, the low molecular weight component is eluted into the hollow structure as an eluate. In the present embodiments, such an issue can be effectively avoided by enhancing the fuel barrier properties of the layer (B).
  • the amount of the eluate is more preferably 25 g/m 2 or less.
  • the lower limit value of the amount of the eluate is ideally 0 g/m 2 , but the amount at which the eluate is not detected by the method described in Examples which will be described later will be substantially a lower limit value.
  • each of the polyamide resin layer (A), the polyamide resin layer (B), and the polyamide resin layer (C) preferably contains a polyolefin.
  • an amount of the polyolefin contained in the polyamide resin layer (B) is from 0.5 P to 2.0 P mass% (preferably 0.6 P mass% or more, further 0.8 P mass% or more, and also preferably 1.2 P mass% or less), and that an amount of the polyolefin contained in the polyamide resin layer (C) is from 0.5 P to 3.0 P mass% (preferably from 1.0 P to 1.6 P mass%), where an amount of the polyolefin contained in the polyamide resin layer (A) is P mass%.
  • the proportions of the polyolefins contained in the layer (A), the layer (B), and the layer (C) are about the same, the low-temperature impact resistance can be further improved.
  • the low-temperature impact resistance tends to be deteriorated with the layer as a starting point.
  • stress is applied to each of the layers in a well-balanced manner, and remarkably excellent low-temperature impact resistance can be achieved.
  • the polyolefin contained in each of the polyamide resin layer (A), the polyamide resin layer (B), and the polyamide resin layer (C) is preferably an acid-modified polyolefin.
  • the polyamide resin layer (A) preferably contains a plasticizer.
  • the hollow structure of the present embodiments preferably includes a combination in which the polyamide resin (a) contains polyamide-12; in the polyamide resin (b1), 70 mol% or more of a diamine-derived structural unit is derived from metaxylylenediamine, and 70 mol% or more of a dicarboxylic acid-derived structural unit is derived from adipic acid; in the polyamide resin (b2), 70 mol% or more of a diamine-derived structural unit is derived from metaxylylenediamine, and 70 mol% or more of a dicarboxylic acid-derived structural unit is derived from sebacic acid; and the polyamide resin (c) contains polyamide-12.
  • the polyamide resin (c) contains polyamide-12.
  • the thicknesses of the polyamide resin layer (A), the polyamide resin layer (B), and the polyamide resin layer (C) in the hollow structure of the present embodiments are preferably such that the thickness of the layer (A) > the thickness of the layer (B) > the thickness of the layer (C). Further, a ratio of the thickness of the layer (A) to the thickness of the layer (B), i.e., the thickness of the layer (A)/the thickness of the layer (B), is preferably from 2.0 to 5.0, more preferably from 2.5 to 4.5.
  • a ratio of the thickness of the layer (B) to the thickness of the layer (C) is preferably from 1.0 to 3.0, more preferably from 1.5 to 2.5.
  • a total thickness of the hollow structure of the present embodiments is not particularly limited as long as it is appropriately set according to the application, but is preferably 10 ⁇ m or more, more preferably 100 ⁇ m or more, even more preferably 500 um or more, and still more preferably 700 ⁇ m or more.
  • An upper limit of the total thickness is preferably 5 mm or less, more preferably 3 mm or less, even more preferably 2 mm or less, and still more preferably 1.5 mm or less.
  • the hollow structure of the present embodiments can be suitably used as a fuel transportation piping material or the like.
  • a fuel transportation piping material for example, it is particularly suitable as a fuel transportation piping material for alkanes such as hexane and octane; aromatic compounds such as toluene and benzene; alcohols such as methanol and ethanol; alcohol gasoline obtained by mixing isooctane, toluene and alcohol; and the like.
  • the hollow structure of the present embodiments can be produced by melt extrusion using an extruder, extrusion into a cylindrical shape through an annular die, shaping through a sizing former that controls the size, cooling in a water tank or the like, and winding up with a take-up machine.
  • the conductive substance is preferably blended into the polyamide resin (c) or the like after being made into a master batch with a thermoplastic resin.
  • the thermoplastic resin to be used in the formation of a master batch is preferably a polyamide resin.
  • At least a part of the hollow structure of the present embodiments may have a wavy region.
  • the wavy region refers to a region formed in a wavy shape, a bellows shape, an accordion shape, a corrugated shape, or the like.
  • the hollow structure having the corrugated region can be easily formed by molding a formed straight tubular hollow structure, and then forming a predetermined wavy shape.
  • a necessary component such as a connector may be added to the hollow structure, or the hollow structure may be formed into a shape such as an L shape or a U shape by bending.
  • a measuring device used in the examples is not readily available due to discontinuation or the like, another device with equivalent performance can be used for measurement.
  • BBSA N-butylbenzenesulfonamide, BM-4, available from Daihachi Chemical Industry Co., Ltd.
  • MXD6 Synthesized according to the following synthesis example.
  • MXD10 Synthesized according to the following synthesis example.
  • PA12 Polyamide 12, UBESTA3030U, available from Ube Industries, Ltd.
  • PA11 Polyamide 11, "Rilsan” P20TLDPA612, available from Arkema Inc.
  • PA612 polyamide 612, UBESTA7034B, available from Ube Industries, Ltd.
  • Carbon black Ketjen Black EC300J, Lion Specialty Chemicals Co., Ltd.
  • the polyamide resin (a) was mixed with the polyolefin (PO) in advance so as to attain the mass proportions indicated in Tables 1 to 6, and the mixture was fed to a twin-screw melt-kneader (available from The Japan Steel Works, Ltd., model: TEX34 ⁇ III), and melt-kneaded at a cylinder temperature of from 180°C to 240°C.
  • a twin-screw melt-kneader available from The Japan Steel Works, Ltd., model: TEX34 ⁇ III
  • Benzenesulfonic acid butylamide as a plasticizer was injected into the middle of a cylinder of the twin-screw melt-kneader by a metering pump to extrude the molten resin in a strand shape, which was then introduced into a water tank, cooled, cut, and vacuum dried to obtain a composition (pellet) for forming the polyamide resin layer (A).
  • the polyamide resins (b1) and (b2) and the polyolefin (PO) were mixed in advance so as to attain the mass proportions indicated in Tables 1 to 6, and the mixture was fed to a twin-screw melt-kneader (available from The Japan Steel Works, Ltd., model: TEX34 ⁇ III), and melt-kneaded at a cylinder temperature of from 180°C to 260°C.
  • the molten resin was extruded in a strand shape, then introduced into a water tank, cooled, cut, and vacuum dried to obtain a composition (pellet) for forming the polyamide resin layer (B).
  • the polyamide resin (c) and the conductive substance were fed to a twin-screw melt-kneader (available from The Japan Steel Works, Ltd., model: TEX34 ⁇ III), and melt-kneaded at a cylinder temperature of from 180°C to 260°C.
  • the molten resin was extruded in a strand shape, then introduced into a water tank, cooled, cut, and vacuum dried to obtain an MB (pellet) of the conductive substance.
  • the polyamide resin (c) was mixed with the polyolefin (PO) and the MB of the conductive substance obtained above in advance so as to attain the mass proportions indicated in Tables 1 to 6, and the mixture was fed to a twin-screw melt-kneader (available from The Japan Steel Works, Ltd., model: TEX34 ⁇ III), and melt-kneaded at a cylinder temperature of from 180°C to 260°C.
  • the molten resin was extruded in a strand shape, then introduced into a water tank, cooled, cut, and vacuum dried to obtain a composition (pellet) for forming the polyamide resin layer (C).
  • a multilayer hollow structure (outer diameter: 8 mm, inner diameter: 6 mm) including layer (A)/layer (B)/layer (C) in this order from the outside was formed, by means of a multilayer hollow structure molding machine equipped with five extruders, using the composition for forming the polyamide resin layer (A), the composition for forming the polyamide resin layer (B), and the composition for forming the polyamide resin layer (C), at an extrusion temperature of 240°C for the layer (A), an extrusion temperature of 260°C for the layer (B), an extrusion temperature of 240°C for the layer (C), and a post-lamination flow channel temperature of 260°C.
  • Comparative Example 6 a multilayer hollow structure including the layer (A) and the layer (C) (outer diameter: 8 mm, inner diameter: 6 mm) was used. The thickness of each layer was as indicated in Tables 1 to 6.
  • the low-temperature impact resistance of the obtained multilayer hollow structure was evaluated by the following method.
  • the hollow structure obtained above was allowed to stand for 4 hours under the condition of -40°C, then a weight of 0.9 kg was dropped from a height of 300 mm to confirm whether a crack occurred, and the low-temperature impact resistance was evaluated as follows. C or higher is a practical level.
  • the amount of the eluate in the polyamide resin (c) and the amount of the eluate from the hollow structure were measured as follows.
  • a single-layer hollow structure (outer diameter: 8 mm, inner diameter: 6 mm) consisted by an all-layer polyamide layer (c) was formed at an extrusion temperature of 240°C and a post-lamination flow channel temperature of 240°C by means of a multilayer hollow structure molding machine equipped with five extruders.
  • a tube completely filled with fuel, in which 42 mL of CE10 (isooctane/toluene/ethanol 45/45/10, volume ratio) was sealed, with stoppers, in 1.5 m of the obtained single-layer hollow structure, was placed under the condition of 60°C for 48 hours. One of the stoppers was then removed and the fuel was transferred to a vessel.
  • the inside of the tube was washed three times with 10 mL of CE10.
  • the vessel was capped, allowed to stand for 24 hours, followed by suction filtration using a filter with a pore size of 0.45 um (PES: polyehersulfone). After drying, the collected material was weighed. The amount of the eluate from the multilayer hollow structure was evaluated as follows. B or higher is a practical level.
  • the adhesion between the layer (A) and the layer (B), and the adhesion between the layer (B) and the layer (C) were evaluated as follows. In Comparative Example 6 in which the layer (B) was not provided, the adhesion was not evaluated.
  • the multilayer hollow structure obtained above was produced, and then allowed to stand at 23°C and 50% relative humidity for one week, and, thereafter, cut in half at a cross section (X in FIG. 2 ) passing through the diameter in the longitudinal direction of the hollow structure to form a flat plate-shaped multilayer body including the polyamide resin layer (A)/the polyamide resin layer (B)/the polyamide resin layer (C).
  • the polyamide resin layer (A) side and the polyamide resin layer (B), and the polyamide resin layer (B) and the polyamide resin layer (C) of the flat plate-shaped multilayer body were separated from each other using tweezers.
  • the hollow structure for fuel of the present invention was excellent in the fuel barrier properties and adhesion between the respective layers, small in amount of the eluate, and excellent in low-temperature impact resistance (Examples 1 to 26).
  • a plasticizer was blended into the polyamide resin layer (A), and thus the low-temperature impact resistance could be more effectively improved (comparison between Examples 1 to 21 and Example 22).
  • the technical value is high in that even when the plasticizer was blended, the amount of the eluate was suppressed to be low.

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